In GSM networks which are enabled for EDGE, so called GSM/EDGE networks, there is always a need to improve the utilization of the network's radio resources. One of the reasons for this is the introduction of so called “smart phones” which are designed to perform a large number of applications which use autonomous access triggers for communication with the application servers. Another reason for the need to improve the utilization of the network's radio resources is the increasing use of so called Machine Type Communication devices, usually referred to as MTC devices.
In a GSM/EDGE network, so called “timing advance” is used for the devices in the network, here referred to generically as Mobile Stations, MSs, with an ongoing RLC/MAC connection in order to align the MSs' transmit time with the receive window in the base stations. The timing advance is estimated by the network and signaled to the MSs via the channel known as the PTCCH channel, the Packet Timing Control Channel. For each MS, a specific PTCCH sub channel is allotted, i.e. one MS—one PTCCH sub channel.
In a GSM/EDGE network, the network does not know whether or not more data will be transmitted from an MS, which means that the network does not know exactly when to disconnect a specific RLC/MAC connection, as a result of which the network usually prolongs the RLC/MAC connections in order to avoid renewed costly access procedures over the Common Control Channel, the CCCH. This, however, results in an increased consumption of PTCCH sub channels, which must be seen against the fact that at present, the number of PTCCH sub channels that can be used simultaneously is 16 per time slot. At present, every 13th TDMA frame in a 52-multiframe with an even frame number is used for a timing advance procedure, by means of the MSs transmitting bursts for timing advance measurements in the uplink and receiving timing advance messages from the network in the downlink, while every 13th TDMA frame in a 52-multiframe with an odd number is called an Idle frame and is used by the MSs for neighboring cell measurements. The term “every 13th TDMA frame” is here used to refer to a system in which frame “number zero”, i.e. the first TDMA frame in a 52-multiframe, is used as the starting point for the counting of “every 13th TDMA frame”.